Performance Tuning Guide

Table of Contents

Introduction
Understanding Bottlenecks
Profiling Tools
Optimization Techniques
Best Practices
Further Resources

Introduction

Performance tuning is the systematic process of identifying and eliminating inefficiencies in a system to achieve faster response times, lower resource consumption, and a smoother user experience. This guide walks you through the essential steps and tools needed to fine‑tune your application.

Understanding Bottlenecks

A bottleneck is any component that limits overall throughput. Common sources include:

CPU saturation
I/O latency (disk, network)
Database query inefficiencies
Blocking JavaScript on the main thread
Excessive memory allocation & garbage collection

Profiling Tools

Before you can optimize, you need accurate metrics.

Server‑side

# Example: Linux perf
sudo perf record -p $(pgrep myservice) -g -- sleep 30
sudo perf report

Browser

Use Chrome DevTools' Performance panel to capture timeline data.

// Capture a trace programmatically
performance.mark('start');
// code to measure
performance.mark('end');
performance.measure('myTask', 'start', 'end');

Optimization Techniques

1. Caching

Leverage HTTP caching headers, Redis, or in‑memory stores.

// Example: Express static cache control
app.use(express.static('public', {
  maxAge: '30d',
  etag: false
}));

2. Database Indexing

# Add index in PostgreSQL
CREATE INDEX idx_users_email ON users(email);

3. Asynchronous Processing

// Queue heavy tasks with BullMQ
const queue = new Queue('jobs');
await queue.add('email', {to: user.email});

4. Reduce Main‑Thread Work

// Web Worker example
const worker = new Worker('worker.js');
worker.postMessage(data);
worker.onmessage = e => console.log('Result', e.data);

Best Practices

Measure before and after each change.
Automate performance regression testing.
Set service‑level objectives (SLOs) and alerts.
Keep critical path code minimal and non‑blocking.